Richmond dispatch. [volume] (Richmond, Va.) 1884-1903, 1887-03-19
Iron Bridges.

Mr.. SNYDER, the author OF the fol-
lowing communication, knows whereof
he writes. He is a practical man. 1t
seems to us that no makes an excellent
suggestion. We quote:
RICHMOND, Va, March II, 1887.
To the Editor Of the Dispatch:
/ take the liberty to write in relation
to the recent bridge horror that &C.
Cured on the Boston and Providence
| railroad.
/ do not for moment doubt that
the testimony of the expert engineers
in relation to the construction of the
bridge, or, as it has been termed by
them, patchwork nondescript," is
very valuable to the public, and will
serve the purpose intended. The only
thing that / want to mention as inyolv-
ing more than can be determined by
theory of engineering, which should
combine practical workmanship with it,
is where they condemn the quality of
the iron used in its construction, where
Mr.. Henry S. Pritchard says: $50 far
as can be judged from outside appear
ances they were made of far from good
iron" Now, Mr.. Editor, that there is
a great amount of poor iron put into
bridges no one will deny but that the
quality of the original iron can be de-
termined by looking at fracture /
do most emphatically deny; and L
start out with the assertion that
where fiber (Which constitutes the
strength of from ever existed it
can never be destroyed so but that
by reheating and reworking it will
come back to its original strength and
toughness. To show how some me-
chanical engineers can be considered
experts is well illustrated by an oc-
currence that took place some years
ago at the Albany Iron-Works in rela-
ton to condemned car-axle on the
New York Central road. The axle was
condemned by the division engineer as
having never been what it was guaran-
teed to be-the very best iron-and
when thrown from the wagon it struck
across another axle, broke in two, and
one journal droppedSff: The other Jour
nal broke on the cars and caused the
accident on the road that condemned
the axle. One part of the axle was
placed in a furnace, reheated. and
rolled, when it was found impossible to
break it (the original fiber having been
restored). That may have been the
case with that iron rod that gave way,
the vibration of the bridge causing that
rod TO crystalline and break. The only
way possible to determine as to the
quality of the iron is to reheat and re-
work it, and if this process does not re-
store the fiber it will be proof pOsitiUe
that the iron was never fit to put into
bridge. What I claim will have
to be done to prevent an occur
renee of a like disaster such as
the abOve--viZ., to remove all the
main truss-rods from an iron bridge
after q certain number of years mo
matter whether they appear all right
or not and substitute new fibrous rods
in their place. The number of years
that these rods can remain in place
safely depends upon the amount of
traffic passing over the bridge, as every
vibration of the bridge crystalhzes to
certain extent the main supporting
rods. Any iron bridge can be tested
with very little trouble and expense by
Just removing one of the truss-rods
nicking and breaking it. If it shows
crystallization all truss-bolts should
then be removed and new ones put in.
1 contend that all expert testimony,
to be valuable, should combine prac-
teal workmanship with theory.
Yours very truly,
S. w. SNYDER.